Method of preparing epoxidized oils and the like



limited rates 3,051,729 METHOD OF PREPARING EPOXIDIZED OILS AND THE LEE Louis I. Hansen and Grant 0. Sedgwick, Minneapolis, Minn., assignors to Archer-Daniels-Midland Company, a corporation of Delaware No Drawing. Filed Sept. 10, 1957, Ser. No. 683,024

11 Claims. (Cl. 260348.5)

This invention relates to a method of preparing epoxy compounds from compounds containing a long-chain unsaturated aliphatic group and particularly long-chain fatty acid esters and long-chain fatty alcohol esters. Heretofore, it has been suggested that such epoxy compounds can be obtained by treating the aliphatic compounds with peracetic acid. In one instance (U.S. Patent No. 2,569,502) the peracetic acid was added to the unsaturated compound in the form of a solution in acetic acid. In another instance (U.S. Patent 2,458,484) aqueous peracetic acid was employed, but in this instance it was stated that vigorous agitation was necessary so that a fine emulsion would be formed.

We have discovered that this reaction can be carried on with great efiiciency if the peracetic acid is formed in the presence of and in admixture with the unsaturated aliphatic compounds and if the concentration of acid relative to the aliphatic compound is maintained sufliciently low to prevent undue splitting of the oxirane ring. To accomplish this, hydrogen peroxide and glacial acetic acid, to which a small amount of sulfuric acid has been added to serve as a catalyst, are mixed together in the presence of the aliphatic compound. It is not crictical as to whether the hydrogen peroxide or acid is first mixed with the aliphatic compound, though ordinarily it will be found simpler to mix the peroxide with the aliphatic material and later add the acid. In any event, the mixing should be carried on progressively over an extended period of time which in commercial operations should ordinarily be 2 hours or more. In such case, only normal stirring is needed, as the progressively formed peracetic acid is readily miscible with the oily mass of the aliphatic compound sufiiciently to cause such peracetic acid to react with the aliphatic compound under the conditions of our operation.

The aliphatic compounds which we use in carrying out this process are primarily the esters of unsaturated higher fatty acids containing from 8 to 22 carbon atoms such, for example, as oleic, erucic, linoleic and linolenic acids and the mixed saturated and unsaturated fatty esters of natural glyceride fats and oils, including tall oil. The alcoholic portion of the ester may be either a saturated or unsaturated monohydric alcohol or a polyhydric alcohol. Examples of such alcohols that we have used include butyl alcohol, iso-octyl alcohol, or the long-chain fatty alcohols derived from the corresponding fatty acids, glycol, glycerol, pentaerythritol and dipentaterythritol. These base materials are representative examples showing monoand poly unsaturation which yield monoand poly epoxy compounds. It may be noted that the fatty acids obtained directly from natural glycerides or comprised in natural glycerides ordinarily are mixtures of various types of fatty acids.

In order to determine the proportions of reactants to 3,05lfl29 Patented Aug. 28, 1962 use, we first determine the degree of unsaturation of the aliphatic body treated and compute the moles of unsaturation. Thus 200 grams of soybean oil with an iodine value of 134.5 is equal to 1.06 moles unsaturation--that is it will combine with l.06 16='16.96 oxygen. For each mole of unsaturation thus computed We use from about 0.7 to 1.1 moles of H 0 Larger amounts of peroxide may be employed but nothing is gained except a more rapid reaction rate but we believe that 5 moles of H 0 per mole of unsaturation is as high as anyone would want to use and certainly 10 moles of H 0 is a top practical limit. The acetic acid (glacial or dilute) may range from 0.3 to 0.7 moles per mole of unsaturation. A preferred range is between 0.4 and 0.6 moles of acetic acid. The sulfuric acid employed is most easily computed in terms of percentage by weight of the acetic acid as this mixture is made in advance and may range from 3% to 8%. A preferred range is between 5% and 7.5% by Weight of the acetic acid. If the sulfuric acid is too loW, the reaction is unduly slow, and if too much is used, splitting of the oxirane ring may occur.

Preferably the hydrogen peroxide is added directly to the aliphatic compound and then the acetic and sulfuric acid are added to the reaction mass gradually over an extended period of time. The acids may be added first and then the peroxide added gradually, but this procedure is not as desirable since sulfation may occur. With the concentrations employed, this reaction is markedly exothermic and substantial cooling must take place. Mixing the reactants slowly as referred to above is also advantageous as undue local heating is thereby prevented. The amount of heat evolved corresponds approximately to 360-400 B.t.u.s per pound of finished product. While cooling is necessary, it is a feature of our invention that during the addition of the acids and the subsequent reaction period the temperature is allowed to rise very much higher than had previously been considered permissible and only ordinary stirring is employed. We have found that the reaction can be carried out successfully at temperatures ranging between F. and 150 F. At the higher temperatures reaction proceeds more rapidly but again there is danger of ring splitting and decomposition of H 0 and We prefer to use temperatures between and F. Within this range the reaction is substantially complete in from 10 to 12 hours.

After the reaction has been completed it is not necessary to Wash the reacted compound. By letting it stand for an hour or two, a layer or gravity separation takes place and the aqueous layer will be found to contain the major proportion of the acetic acid, with substantial percentages of hydrogen peroxide. This latter layer can be used further. For example, if the aqueous layer contains approximately 10% of hydrogen peroxide, it may be reacted with fresh oil at the temperature stated until the quantity of hydrogen peroxide is reduced, say, to about 1%. This aqueous layer may then be removed for recovery of the acetic acid content by rectification. The oil treated in this way will be only partially epoxidized but may then be treated with a fresh charge of hydrogen peroxide and acetic acid (containing sulfuric acid) in an amount suflicient to raise the oxirane level to the desired point, say approximately 6%. After the conclusion of this second reaction, the spent aqueous layer from it is again available for reaction with fresh oil. By employing this cyclic process virtually all of the hydrogen peroxide charged into the reaction mixture is utilized.

The cyclic process of using the water-soluble bodies from the reacted product for treating additional quantities of the unsaturated organic compound as set forth in the foregoing paragraph is included herein in order to give a description of a complete commercial process. However, this particular step in the process is not claimed as our invention, but we believe that the same is the invention of Arvi W. Wahlroos who was a'party to our original application as a joint applicant.

condensate may also be rectified and reused so that very little acetic acid is wasted.

Our invention may readily be understood from the following illustrative examples:

7 Example I The ingredients used were 652 pounds of soybean oil, 78.1 pounds of glacial acetic acid, 224 pounds of 49.8% H equivalent to 111.6 pounds of 100% H 0 and 112.4 pounds of water and 3.92 pounds of concentrated sulfuric acid;

The reaction was carried out by charging all of the soybean oil, all of the peroxide and 20% of the mixture of acetic and sulfuric acid into the reaction vessel. The remaining acetic acid mixed with the sulfuric acid was added gradually over'a four-hour period as follows:

30% of the remaining mixed acid was added during the first hour, 20% during each of the second and third hours and 30% during the fourth hour. 75% of the entire heat of reaction had been liberated at the end of the third hour. The temperature was allowed to rise to 132 F. and maintained'at approximately this point during the reaction period. After 12 hours the reaction mixture was treated with dilute alkali using a 50% excess over the amount necessary to neutralize the sulfuric acid, and allowed to settle. The oily layer was then separated from the aqueous layer in the usual manner incident to layer or gravity. separation.

The oily layer was vacuum steam distilled up to a temperature of 250 F. In this distillation the temperature was first raised to 150 F. at a pressure of 76 mm. of mercury (absolute) at a rate of rise of 2 F. per minute which may require 60 minutes, depending on the amount of water present in the oil. In this way the temperature -is brought up to 180 F steaming at the rate of 3 pounds of steam per hour per 100 pounds of oil. The temperature was then held at 180 F. at the same pressure and steamed at the same rate until the acid value wisdom to 2. This required about an hour. The temperature was then raised to 240 F., again at the rate of 2 F. per minute but at a pressure of 25 mm. of mercury (absolute) and steaming was continued'at the rate of 2 pounds of steam per hour per 100 pounds of oil and held at 240 F. until a bleaching effect was accomplished. This took about 10 minutes. The steam was then cut ofi and the batch cooled and filtered. The oxirane content of the product was 6.12% and the weight of the oil had increased to 692pounds.

The acid distilled off plus acid recovered from the aqueous layer was rectified for reuse.

Example [I In this example we used 1174 grams of soybean oil having an iodine value of 134 equivalent to 1.06 moles of unsaturation for each 200 grams. With this we used 140.9 grams of acetic acid equivalent to 0.4 mole of acetic, and for each 1.06 moles of unsaturation 344 grams 4 of 46.7% H 0 was used, equivalent to 159.9 grams of H 0 This was equal to 0.8 mole of H 0 for each 1.06 moles of unsaturation. 7.04 grams of sulfuric acid was mixed with the acetic acid.

The soybean oil was charged into a stainless steel beaker equipped with a stirrer and thermometer. This beaker was placed in a water bath which could be used for cooling or heating. After the oil had been heated a temperature of 134 F. the peroxide was added. This was followed by the periodic addition of the solution containing the acetic acid and sulfuric acid during an interval of 2% hours. The reaction was quite exothermic for five hours, requiring cooling. After 12 hours of reaction at 132 F. an oxirane content of 5.75% was obtained. The sulfuric acid in the reaction product was first neutralized using a 40% excess of dilute NaOH solution and then the mixture was team distilled at reduced pressure to 250 F. The final product had a viscosity of 3.6 seconds (bubble travel in a Gardner-Holt The oil mixture was heated to F. Then the hydrogen peroxide and 70% of the acetic acid were added. When the temperature reached 133 F. a mixture of the remaining 30% of acetic acid with the sulfuric acid is proportionated in over a period of about 2 hours. After the mixed acids addition was completed the reaction Was continued for a total of about 12 hours. The reaction was stopped and the mixture was allowed to stand at room temperature until separation of oil and aqueous phases was complete. p

The 'oily layer was transferred to a vessel in which it was treated with a dilute solution of sodium hydroxide containing 1% times that equivalent to the residual sulfuric acid.

' The oily product was then stripped with steam at reduced pressure up to 230 F. for /2 hour to remove residual volatile acidity and water. It was then cooled The oil was heated to 140 F. and the hydrogen peroxide and 70% of the acetic acid were added. When the temperature reached 133 F., the. mixture of the remaining 30% of acetic acid with the sulfuric acid was added portionwis'e as before, Then the reaction was continued for a total of 14 hours. The reaction was then stopped and the reaction mixture was allowed to stand at room temperature until separation of oil and aqueous phases was complete.

The oily layer was then transferred to a vessel in which it was treated with a dilute solution of sodium hydroxide containing 1 /2 times that equivalent to residual sulfuric acid.

The sulfuric acid free oily product was stripped with steam at reduced pressure up to 230 F. for half an hour to remove volatile acidity and water. cooled to 150 F. and filtered.

The clear product had the following analysis:

It was then The ester was heated to about 135l40 F.; then hydrogen peroxide and 70% of the acetic acid was added. When the temperature reached to 130 F. the mixture of the remaining 30% of acetic with the sulfuric acid was added portionwise as in Example H1. The reaction was then continued for a total of hours. The reaction was then stopped and the reaction mixture allowed to stand at room temperature until the separation of oil and aqueous phases was complete. The oily layer was transferred to a vessel in which it was treated with a dilute solution of calcium hydroxide (dispersion) containing 1% times the equivalent of residual sulfuric acid.

The sulfuric acid free oily product was stripped with steam at reduced pressure up to 230 F. for half an hour to remove the residual volatile acidity and water. It was then cooled to 150 F. and filtered.

The ester was heated to 135140 F.; then hydrogen peroxide and 70% of the acetic acid were added. When the temperature had reached 130 F.l33 F., the mixture of the remaining 30% of acetic acid with the sulfuric acid was added portionwise as in Example III. The reaction was continued at 133134 F. for a total of 10 hours. The reaction was stopped and the reaction mixture was allowed to stand at room temperature until the separation of oil and aqueous phases was complete.

The oily layer was transferred to a vessel in which it was treated with a dilute solution of sodium hydroxide containing 1% times the equivalent of residual sulfuric acid.

The sulfuric acid free oily product was stripped with steam at reduced pressure up to 230 F. for half an hour. It was then cooled to 150 F. and filtered.

The clear product had the following analysis:

Percent \oxirane 4.02

The ester was heated to 130 F. Then hydrogen peroxide and 70% of acetic acid were added. When temperature had reached 125 F., the mixture of remaining-30% acetic acid with the sulfuric acid was added porti-onwise over a 2 hour period. The reaction was continued at 131-133 F. for an additional 5% hours.

The reaction was stopped and the mixture was allowed to stand at room temperature until the oily and aqueous phases were complete.

The oily layer was transfer-red to a vessel where it was treated with a dilute solution of sodium hydroxide containing 1% times the equivalent of residual sulfuric acid.

The sulfuric acid free oily product was stripped with steam at reduced pressure up to 230 F. for half an hour to remove residual volatile acidity and water. It was then cooled to 150 F. and filtered.

The clear product had the following analysis:

Percent oxirane 5.04 I.V. 14.8

OH value 32.3

Example VIII In this example we used 650 pounds of soybean oil having 1.06 moles of unsaturation per 200 grams. We used 78 pounds of acetic acid again equivalent to 0.4 mole of acetic per 1.06 moles of unsaturation. in this run we employed 240 pounds of 46.3% H 0 equivalent to one mole of H 0 for each 1.06 moles of unsaturation. 3.9 pounds of sulfuric acid was mixed with the acetic acid.

This run was made in a four-barrel stainless steel tank equipped with heating or cooling coils and stirrer. The oil was put in this tank and 48 pounds of the 46.3% peroxide was added. When a temperature of 125 F. was reached, the remaining 80% of peroxide and the solution of sulfuric acid and glacial acetic acid were added separately and proportionally as follows: 30% of each during the first hour, 20 of each during the second hour, 20% of each during the third hour and the remaining 30% of each during the fourth hour.

The batch was held at F. for 13 hours at which time the stirrer was stopped and after 2% hours settling the aqueous layer was drawn 0E. The oily layer was treated with dilute sodium hydroxide solution containing 1% equivalents for each equivalent of sulfuric acid present. The reaction product was then transferred to a stainless steel autoclave and steam-distilled at reduced pressure up at 250 F. The acetic acid recovered was rectified for reuse.

The aqueous layer amounting to 217 pounds contained 28% of acetic acid, 1.2% of sulfuric acid and 4.8% of active oxygen as peracetic acid. This material was reacted for 12 hours at F. with 642 pounds of fresh soybean oil. The percent of active oxygen in the aqueous layer then obtained by centrifuging a small sample of the reaction mixture was reduced to less than 1. At this point agitation was stopped and the reaction mixture was permitted to settle. The aqueous layer was drawn off and after decomposing the remaining active oxygen, the acetic acid was recovered.

The oily reaction product with an oxirane value of 1.2 was further reacted at 130 F. with 225 pounds of 50% H 0 87.8 pounds of acetic acid (80%) and 4 pounds of sulfuric acid. These reactants were added proportionally in the manner already described. After a total of 10 hours the oxirane content had reached 6%. The stirrer was then stopped and the batch was allowed to settle. The aqueous layer was withdrawn for reuse as described and the oily layer after neutralization was given the same type of steam distillation as was used in the ethylene glycol (Acintol D'a product of Arizona Chemical Co.) was heated to about 135 F.140 F. and the hydrogen peroxide and 70% of the acetic acid were added. When the temperature had reached to 133 F.

the mixture of the remaining 30% acetic acid with the sulfuric acid was added portionwise over a 2-hour period. The reaction was continued at 132 F.134 F. for an additional 8 hours. The reaction was stopped and the reaction mixture was allowed to stand until the separation of oil and aqueous phases was completed.

The oily layer was transferred to a vessel in which it was treated with calcium hydroxide dispersion containing 1% times the equivalent of the residual sulfuric acid.

The sulfuric acid free oily product was stripped with steam at reduced pressure up to 230 F. for half an hour The ester was heated to about 135-140 F., then 70% of the acetic acid, 27 parts, and 59 parts 50% of hydrogen peroxide were added. The temperature dropped to 130 F. and the remaining acetic acid, 11.6 parts, was

mixed with 1.94 parts sulfuric acid and this solution added portionwise over a two hour period. The remaining hydrogen peroxide, 59 parts, was likewise added portionwise over a 2 hour period. The reaction was exothermic for at least 6 hour and was held for 12 hours additional atl34 F. The stirrer was then stopped and reaction allowed to separate into two layers. After one hour complete separation had occurred and the oily layer was transferred to another reactor in which it was treated with a dilute dispersion of calcium hydroxide containing 1% times the equivalent of the residual sulfuric acid in the aqueous layer remaining in the oily layer.

The sulfuric acid free oily layer was stripped with stream at reduced pressure up to 230 F. Steaming was continued at 230 F. and 4 mm. of Hg pressure until the acid value 'had been reduced to 0.8. It was then cooled to 150 F. and filtered.

Analysis of clear product:

Percent oxiran 5.1 I.V. 4.3 OH val 12 Acid No 0.82

It will be seen from the foregoing examples that we are able to obtain a high percentage of oxidized oil which may run up close to 80% and at the same time we operate our process extremely eificiently, as there is very little loss of reagents.

Our process is primarily a one-step procedure involving all the reactants and forming peracetic acid in situ and forming the epoxidized product in the presence of sulfuric acid. Such a process is highly efficient both in its utilization of chemicals and in the use of apparatus.

As regards the utilization of chemicals, it will be found that we use only a small fraction of the amount of acetic acid employed in the known two-step processes ivigorous agitation."

In our process we'have only alowconoentration of the acetic acid present which renders it unnecessary to wash out unused reactants with water, and we can distill oil the acetic acid with no appreciable splitting of the oxirane ring. This 'absence'of splitting is also a'factor in permitting'us to use temperatures in excess of P. which makes for greater efiiciency;

Due to the high percentage of epoxidized product which is present in the reaction mass (which may reach as. high a percentage as about 79%) and the fact that we do"not"add"w'ater to remove unused reactants, our equipment need handle only a fraction of the weight of product previously required to get a specified result.

It is understood that the examples given are only by way of illustration and are not intended to constitute a limitation upon the scope of our invention.

This application is a continuation-in-part of our earlier application, Serial No. 333,372, filedJanuary 26, 1953, now abandoned.

What we claim is:

1. The process for the epoxidation of a higher fatty acid ester which comprises introducing and mixing into the said ester at a temperature of about 90-150 F., 0.7-10 moles of hydrogen peroxide and 0.3-0.7 mole of acetic acid for each mole of unsaturation of the said ester, and about 3%8% of sulfuric acid on the weight of the acetic acid, the said introducing being eifected over a period of about 2 hours or more and continuing the reaction at the said temperature until epoxidation of the ester is eifected.

2. A process as specified in claim 1 which includes the further steps of removing water and water-soluble bodies from the epoxidized ester by gravity separation, neutralizing sulfuric acid in the epoxidized ester, and then subjecting the neutralized material to distillation to drive off residual acetic acid.

3. The process for the epoxidation of a higher fatty acid glyceride which comprises introducing and mixing into the said glyceride at a temperature of about 90- F., 0.75 moles of hydrogen peroxide and 0.30.7 mole of acetic acid for each mole of unsaturation of the said glyceride, and about 3%-8% of sulfuric acid on the weight of the acetic acid, the said introducing being eifected over a period of at least 2% hours, and continuing the mixing at the said temperature until epoxidation of the glyceride is effected.

4. A process as specified in claim 1 in which the ester employed is soybean oil.

5. A process as specified in claim 1 in which the ester employed is an ester of a fatty acid having from 8 to 22 carbon atoms combined with a monohydric alcohol.

6. A process as specified in claim 1 in which the ester employed is an ester of'a mixture of 'fatty acids having from 8 to 22 carbon atomscombined with an alcohol selected from the group consisting of the monohydric and polyhydric alcohols.

7. A process as specified in claim .1 in which the sulfuric acid is prediluted with at least a portion of the acetic acid before being introduced into the mixture.

8. The method of epoxidizing an ester of an unsaturated higher fatty acid which comprises adding with stirring to said ester about 0.3 to 0.7 mole of acetic acid for each mole of unsaturation of said higher fatty acid together with about 3%8% of sulfuric acid on the weight of the acetic acid and about 0.7-5 moles of hydrogen peroxide for'each mole of unsaturation of said higher fatty acid, the hydrogen peroxide and said combined acids being added separately, heating the reaction mixture to a temperature between 90 and 150 F.

and maintaining the temperature during the epoxidation reaction.

9. The method as specified in claim 8 in which all of the acids are addedto said higher fatty acid ester after the addition of the hydrogen peroxide is completed.

The method of epOXidiZillg all ester of an 1111- 11. The method specified in claim 10 which includes Saturated higher fatty acid which COmPIiSES iXing with the step of adding the acids to said ester after the addithe ester from about t0 1110165 of hydrogen P tion of substantially all of the hydrogen peroxide. oxide for each mole of unsaturatiou of said higher fatty acid, from about 0.3 to 0.7 mole of acetic acid for each 5 References Cited in the file of this patent mole of unsaturation of said higher fatty acid, and from about 3% to 8% of sulfuric acid based on the weight UNITED STATES PATENTS of acetic acid, heating the reaction mixture to a tem- 2,453,434 Terry et 4, 1949 perature of about 90 F. to about 150 F. and maintain- 2,801,253 Greenspan y 1957 ing such temperature during reaction. 10 2,813,878 Wahlroos Nov. 19, 1957 

1. THE PROCESS FOR THE EPOXIDATION OF A HIGHER FATTY ACID ESTER WHICH COMPRISES INTRODUCING AND MIXING INTO THE SAID ESTER AT A TEMPERATURE OF ABOUT 90*-150*F., 0.7-10 MOLES OF HYDROGEN PEROXIDE AND 0.3-0.7 MOLE OF ACETIC ACID FOR EACH MOLE OF UNSATURATION OF THE SAID ESTER, AND ABOUT 3%-8% OF SULFURIC ACID ON THE WEIGHT OF THE ACETIC ACID, THE SAID INTRODUCING BEING EFFECTED OVER A PERIOD OF ABOUT 2 HOURS OR MORE AND CONTINUING THE REACTION AT THE SAID TEMPERATURE UNTIL EPOXIDATION OF THE ESTER IS EFFECTED. 